Some hard drives are designed with the assumption that significant movement of the drive may occur while the hard drive is operating. As such, the hard drives may include measures to compensate for shock and vibration that may occur during operation. However, even in a fixed installation, shock and vibration may be present present. For example, in a multi-drive configuration such as a disk array, the cooling fans as well as the drives themselves may generate vibrations that may be transmitted between hard drives through the structure in which they are mounted. This vibration can affect, among other things, tracking of the read/write head over the recording media. In other installations, speakers, force-feedback devices, and other vibration generating components may cause similar disturbances that affect a hard drive.
As areal density of hard drives increase, the track pitch may decrease significantly, leading to increased sensitivity to vibration that affects the read/write head. As a result, additional control mechanisms may be used to ensure read/write heads can reliably track over recording media with reduced track pitch.